This invention relates generally to reciprocating control of double acting multistage hydraulically driven gas compressors using a free floating piston.
In more particular aspects this invention relates to reciprocating control of a double acting hydraulically driven gas compressor using a free floating piston, which responds to pressure peaks generated in the hydraulic system by stopping of the free floating piston at the end of the compression stroke, providing a compressing mechanism with minimum clearance volume.
In still more particular aspects this invention relates to relief valve mechanism limiting pressure peaks, due to reversal of the free floating piston, to a pressure, higher by a constant pressure differential than the discharge pressure of the gas compressor.
Control of reciprocating hydraulically driven free floating compressor piston presents a difficult problem. Deceleration and stopping of the piston before the end of its stroke provides a large clearance volume, which drastically reduces the displacement of the compressor. Stopping of the free floating piston against the cover, very beneficial from the clearance volume standpoint, also introduces high pressure peaks in the hydraulic system.